Tagged: Caltech Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 4:17 pm on January 9, 2020 Permalink | Reply
    Tags: Caltech, New Quantum Algorithm, , Quantum imaginary time evolution, The Hamiltonian represents the energy of the system   

    From Caltech: “Caltech Researchers Develop New Quantum Algorithm” 

    Caltech Logo

    From Caltech

    December 18, 2019
    Emily Velasco
    626‑395‑6487
    evelasco@caltech.edu

    1

    Quantum computers, just like classical computers, are only as good as the instructions that we give them. And although quantum computing is one of the hottest topics in science these days, the instructions, or algorithms, for quantum computers still have a long way to go to become useful. Garnet Chan, Caltech’s Bren Professor of Chemistry, is tackling this problem. In a new paper [Nature Physics], he describes how he, together with Fernando Brandao, Bren Professor of Theoretical Physics, and Austin Minnich, professor of mechanical engineering and applied physics, developed an algorithm for quantum computers that will help them find use in simulations in the physical sciences.

    The algorithm is derived from one already in use in classical computing called imaginary time evolution. Chan’s new algorithm, tailored to run on quantum computers, has been fittingly dubbed quantum imaginary time evolution and allows a user to find the lowest energy of a given molecule or material.

    We sat down with Chan to talk about his research and what it means for quantum computing.

    In lay terms, what have you achieved with your new research?

    There has been a lot of interest in what kind of problems a quantum computer can potentially help to solve in the physical sciences. One problem that many people are interested in is how to simulate the ground states of molecules and materials. Our new paper proposes a way to calculate ground states of Hamiltonians that runs on near-term quantum computers with very few resources.

    What is a Hamiltonian, and why would you want to know its ground state?

    The Hamiltonian represents the energy of the system, and the ground state of the Hamiltonian is the most stable state of the problem. Most physical systems, under ordinary conditions, are not too excited, and thus live close to their ground states.

    For example, if we want to do a simulation of water, we could look at how water behaves after it has been blasted into a plasma—an electrically charged gas—but that’s not the state water is usually found in; it is not the ground state of water. Ground states are of special interest in understanding the world under ordinary conditions.
    Why is it challenging to perform these calculations on a quantum computer?

    Quantum devices currently decohere after a short period of time, which means that the computer needs to be recalibrated and cannot be used for calculations until it is set up again. That means we need to find a way to perform calculations on them very efficiently so we solve our problem before decoherence occurs.

    What does your algorithm do?

    There have been many proposals for how to obtain ground states on quantum computers. One of the first was by Alexei Kitaev [Caltech’s Ronald and Maxine Linde Professor of Theoretical Physics and Mathematics], but unfortunately that algorithm, known as phase estimation, requires too many instructions and cannot be implemented before current quantum computers decohere. Another way, called the variational approach, is very simple to implement but in practice turns out not to be so accurate. We wanted to find a way that could be potentially as accurate as phase estimation but which could also be practically programmed on today’s quantum computers.

    What does the development of this algorithm mean for quantum computing?

    Quantum computers are still very new, and we still need to learn what they will be useful for. Because we can barely use them right now, part of the answer lies in developing efficient programs that can be run on them in very little time. Our work provides a basis for assessing the capabilities of quantum computers as they are now, which will help tell us what we can expect in the future.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 7:05 pm on January 8, 2020 Permalink | Reply
    Tags: , , , Caltech, , , NOAO WIYN Telescope, The name NEID is derived from the word meaning "to see" in the native language of the Tohono O'odham on whose land Kitt Peak is located.   

    From Caltech: “Measuring the Minute Wobbles of Stars” 

    Caltech Logo

    From Caltech

    January 08, 2020

    Whitney Clavin
    (626) 395‑1944
    wclavin@caltech.edu

    1
    NEID– A new instrument aims to detect tiny stellar motions caused by the tug of Earth-mass planets. Caltech/Penn State

    NEID chamber for the WIYN telescope. Photos courtesy of NOAO WIYN and Washburn Labs-University of Wisconsin.

    Penn State NEID spectrographic instrument schematic for the WIYN telescope at Kitt Peak, AZ, USA Altitude 2,096 m 6,877 ft

    4
    First-light spectrum of the star 51 Pegasi as captured by NEID on the WIYN telescope with a blowup of a small section of the spectrum. The right panel shows the light from the star, highly dispersed by NEID, from short wavelengths (bluer colors) to long wavelengths (redder colors). The colors shown, which approximate the true color of the starlight at each part of image, are included for illustrative purposes only. The region in the small white box in the right panel, when expanded (left panel), shows the spectrum of the star (longer dashed lines) and the light from the wavelength calibration source (dots). Deficits of light (dark interruptions) in the stellar spectrum, are due to stellar absorption lines — “fingerprints” of the elements that are present in the atmosphere of the star. By measuring the subtle motion of these features, to bluer or redder wavelengths, astronomers can detect the “wobble” of the star produced in response to its orbiting planet.
    Credit: Guðmundur Kári Stefánsson/Princeton University/Penn State/NSF’s National Optical-Infrared Astronomy Research Laboratory/KPNO/AURA

    As the planets in our solar system go around the sun, they tug on it, causing it to wobble. Jupiter, our most massive planet, yanks on our sun to a significant degree, whereas Earth, which is tiny by comparison, exerts a much weaker tug.

    Other Earth-like planets circling stars in our galaxy would similarly cause minute wobbles in their stars, so planet hunters search for these wobbles using a technique called the radial velocity method. So far, they have not found any exoplanets like the Earth, but that may change with a new telescope instrument called NEID.

    “We may be able to find the first Earth-mass planets with NEID,” says Arpita Roy, a Caltech postdoctoral scholar who works with Professor of Astronomy Andrew Howard and who helped build NEID with a team led by researchers at Penn State. Roy says that the instrument can currently detect stellar motions of about 30 centimeters per second but that their ultimate goal is to try to get down to 10 centimeters per second on certain stars—the speed our sun moves due to Earth’s tug.

    NEID was recently installed on the 3.5-meter WIYN telescope at Kitt Peak National Observatory in Southern Arizona and made its first observations on December 13, 2019.

    NOAO WIYN Telescope, Kitt Peak National Observatory, Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers (55 mi) west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    Kitt Peak National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    The instrument is being developed as part of a joint initiative between NASA and the National Science Foundation. The name NEID is derived from the word meaning “to see” in the native language of the Tohono O’odham, on whose land Kitt Peak is located.

    A news release about NEID’s “first light” observations, from NSF’s National Optical-Infrared Astronomy Research Laboratory, which operates the Kitt Peak National Observatory, is online at: https://www.nationalastro.org/news/neid-exoplanet-instrument-sees-first-light/.

    Roy is also the project scientist for an upcoming instrument similar to NEID, called the Keck Planet Finder, scheduled to be installed at the W. M. Keck Observatory on Maunakea, Hawaii, in 2021.

    Keck Observatory, operated by Caltech and the University of California, Maunakea Hawaii USA, 4,207 m (13,802 ft)

    Says Roy, “In many ways, NEID is paving the way for the Keck Planet Finder, which should be able to find Earth-mass planets even faster.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 11:20 am on December 26, 2019 Permalink | Reply
    Tags: 'edscottite', A rare form of iron-carbide mineral that's never been found in nature., Analyses have revealed traces of gold and iron along with rarer minerals such as kamacite; schreibersite; taenite; and troilite., , Caltech, Distinctive black-and-red rock, , Now we can add edscottite to that list., The Wedderburn meteorite   

    From Caltech via Science Alert: “Scientists Have Officially Found a Mineral Never Before Seen in Nature” 

    Caltech Logo

    From Caltech

    via

    ScienceAlert

    Science Alert

    25 DEC 2019
    PETER DOCKRILL

    1
    The Wedderburn meteorite. (Museums Victoria/CC BY 4.0)

    It was found along the side of a road in a remote Australian gold rush town. In the old days, Wedderburn was a hotspot for prospectors – it occasionally still is – but nobody there had ever seen a nugget quite like this one.

    The Wedderburn meteorite, found just north-east of the town in 1951, was a small 210-gram chunk of strange-looking space rock that fell out of the sky. For decades, scientists have been trying to decipher its secrets, and researchers just decoded another.

    In a study published in August [American Mineralogist] this year, led by Caltech mineralogist Chi Ma, scientists analysed the Wedderburn meteorite and verified the first natural occurrence of what they call ‘edscottite’: a rare form of iron-carbide mineral that’s never been found in nature.

    Since the Wedderburn meteorite’s spacey origins were first identified, the distinctive black-and-red rock has been examined by numerous research teams – to the extent that only about one-third of the original specimen still remains intact, held within the geological collection at Museums Victoria in Australia.

    The rest has been taken away in a series of slices, extracted to analyse what the meteorite is made from. Those analyses have revealed traces of gold and iron, along with rarer minerals such as kamacite, schreibersite, taenite, and troilite. Now we can add edscottite to that list.

    The edscottite discovery – named in honour of meteorite expert and cosmochemist Edward Scott from the University of Hawaii – is significant because never before have we confirmed that this distinct atomic formulation of iron carbide mineral occurs naturally.

    Such a confirmation is important, because it’s a pre-requisite for minerals to be officially recognised as such by the International Mineralogical Association (IMA).

    A synthetic version of the iron carbide mineral has been known about for decades – a phase produced during iron smelting.

    But thanks to the analysis by Chi Ma and UCLA geophysicist Alan Rubin, edscottite is now an official member of the IMA’s mineral club, which is more exclusive than you might think.

    “We have discovered 500,000 to 600,000 minerals in the lab, but fewer than 6,000 that nature’s done itself,” Museums Victoria senior curator of geosciences Stuart Mills, who wasn’t involved with the new study, told The Age.

    As for how this sliver of natural edscottite ended up just outside of rural Wedderburn can’t be known for sure, but according to planetary scientist Geoffrey Bonning from Australian National University, who wasn’t involved with the study, the mineral could have formed in the heated, pressurised core of an ancient planet.

    Long ago, this ill-fated, edscottite-producing planet could have suffered some kind of colossal cosmic collision – involving another planet, or a moon, or an asteroid – and been blasted apart, with the fragmented chunks of this destroyed world being flung across time and space, Bonning told The Age.

    Millions of years later, the thinking goes, one such fragment landed by chance just outside Wedderburn – and our understanding of the Universe is the richer for it.

    3
    Scanning electron microscopy image (colorized) showing edscottite in the polished Wedderburn section from the UCLA Meteorite Collection. Image credit: Ma & Rubin, doi: 10.2138/am-2019-7102.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 2:16 pm on December 21, 2019 Permalink | Reply
    Tags: "Scientists Identify Almost 2 Million Previously "Hidden" Earthquakes", , Caltech, , , , ,   

    From Caltech: “Scientists Identify Almost 2 Million Previously “Hidden” Earthquakes” 

    Caltech Logo

    From Caltech

    April 18, 2019 [Just found this is a search]
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    A closer look at seismic data from 2008–17 expands Southern California’s earthquake catalog by a factor of 10.

    1
    Seismic activity associated with the Cahuilla earthquake swarm in Southern California’s Anza Valley. Filling out the earthquake catalogue using template matching shows the swarm in greater detail. The color of each seismic event records its depth, and so the rainbow-like appearance of the swarm indicates the shallow-to-deep slant of the fault, not previously visible from earlier data.

    Pouring through 10 years’ worth of Southern California seismic data with the scientific equivalent of a fine-tooth comb, Caltech seismologists have identified nearly two million previously unidentified tiny earthquakes that occurred between 2008 and 2017.

    Their efforts, published online by the journal Science on April 18, expand the earthquake catalog for that region and period of time by a factor of 10—growing it from about 180,000 recorded earthquakes to more than 1.81 million. The new data reveal that there are about 495 earthquakes daily across Southern California occurring at an average of roughly three minutes apart. Previous earthquake cataloging had suggested that approximately 30 minutes would elapse between seismic events.

    This 10-fold increase in the number of recorded earthquakes represents the cataloging of tiny temblors, between negative magnitude 2.0 (-2.0) and 1.7, made possible by the broad application of a labor-intensive identification technique that is typically only employed on small scales. These quakes are so small that they can be difficult to spot amid the background noise that appears in seismic data, such as shaking from automobile traffic or building construction.

    “It’s not that we didn’t know these small earthquakes were occurring. The problem is that they can be very difficult to spot amid all of the noise,” says Zachary Ross, lead author of the study and postdoctoral scholar in geophysics, who will join the Caltech faculty in June as an assistant professor of geophysics. Ross collaborated with Egill Hauksson, research professor of geophysics at Caltech, as well as Daniel Trugman of Los Alamos National Laboratory and Peter Shearer of Scripps Institution of Oceanography at UC San Diego.

    To overcome the low signal-to-noise ratio, the team turned to a technique known as “template matching,” in which slightly larger and more easily identifiable earthquakes are used as templates to illustrate what an earthquake’s signal at a given location should, in general, look like. When a likely candidate with the matching waveform was identified, the researchers then scanned records from nearby seismometers to see whether the earthquake’s signal had been recorded elsewhere and could be independently verified.


    Using powerful computers and a technique called template matching, scientists at Caltech have identified millions of previously unidentified tiny earthquakes. The new data reveal that there are about 495 earthquakes daily across Southern California, occurring at an average of roughly three minutes apart. This graphic shows the earthquakes recorded near Cahuilla, California from 2016-2017.

    Template matching works best in regions with closely spaced seismometers, since events generally only cross-correlate well with other earthquakes within a radius of about 1 to 2 miles, according to the researchers. In addition, because the process is computationally intensive, it has been limited to much smaller data sets in the past. For the present work, the researchers relied on an array of 200 powerful graphics processing units (GPUs) that worked for weeks on end to scan the catalog, detect new earthquakes, and verify their findings.

    However, the findings were worth the effort, Hauksson says. “Seismicity along one fault affects faults and quakes around it, and this newly fleshed-out picture of seismicity in Southern California will give us new insights into how that works,” he says. The expanded earthquake catalog reveals previously undetected foreshocks that precede major earthquakes as well as the evolution of swarms of earthquakes. The richer data set will allow scientists to gain a clearer picture of how seismic events affect and move through the region, Ross says.

    “The advance Zach Ross and colleagues has made fundamentally changes the way we detect earthquakes within a dense seismic network like the one Caltech operates with the USGS. Zach has opened a new window allowing us to see millions of previously unseen earthquakes and this changes our ability to characterize what happens before and after large earthquakes,” said Michael Gurnis, Director of the Seismological Laboratory and John E. and Hazel S. Smits Professor of Geophysics

    See the full article here .

    Earthquake Alert

    1

    Earthquake Alert

    Earthquake Network projectEarthquake Network is a research project which aims at developing and maintaining a crowdsourced smartphone-based earthquake warning system at a global level. Smartphones made available by the population are used to detect the earthquake waves using the on-board accelerometers. When an earthquake is detected, an earthquake warning is issued in order to alert the population not yet reached by the damaging waves of the earthquake.

    The project started on January 1, 2013 with the release of the homonymous Android application Earthquake Network. The author of the research project and developer of the smartphone application is Francesco Finazzi of the University of Bergamo, Italy.

    Get the app in the Google Play store.

    3
    Smartphone network spatial distribution (green and red dots) on December 4, 2015

    Meet The Quake-Catcher Network

    QCN bloc

    Quake-Catcher Network

    The Quake-Catcher Network is a collaborative initiative for developing the world’s largest, low-cost strong-motion seismic network by utilizing sensors in and attached to internet-connected computers. With your help, the Quake-Catcher Network can provide better understanding of earthquakes, give early warning to schools, emergency response systems, and others. The Quake-Catcher Network also provides educational software designed to help teach about earthquakes and earthquake hazards.

    After almost eight years at Stanford, and a year at CalTech, the QCN project is moving to the University of Southern California Dept. of Earth Sciences. QCN will be sponsored by the Incorporated Research Institutions for Seismology (IRIS) and the Southern California Earthquake Center (SCEC).

    The Quake-Catcher Network is a distributed computing network that links volunteer hosted computers into a real-time motion sensing network. QCN is one of many scientific computing projects that runs on the world-renowned distributed computing platform Berkeley Open Infrastructure for Network Computing (BOINC).

    The volunteer computers monitor vibrational sensors called MEMS accelerometers, and digitally transmit “triggers” to QCN’s servers whenever strong new motions are observed. QCN’s servers sift through these signals, and determine which ones represent earthquakes, and which ones represent cultural noise (like doors slamming, or trucks driving by).

    There are two categories of sensors used by QCN: 1) internal mobile device sensors, and 2) external USB sensors.

    Mobile Devices: MEMS sensors are often included in laptops, games, cell phones, and other electronic devices for hardware protection, navigation, and game control. When these devices are still and connected to QCN, QCN software monitors the internal accelerometer for strong new shaking. Unfortunately, these devices are rarely secured to the floor, so they may bounce around when a large earthquake occurs. While this is less than ideal for characterizing the regional ground shaking, many such sensors can still provide useful information about earthquake locations and magnitudes.

    USB Sensors: MEMS sensors can be mounted to the floor and connected to a desktop computer via a USB cable. These sensors have several advantages over mobile device sensors. 1) By mounting them to the floor, they measure more reliable shaking than mobile devices. 2) These sensors typically have lower noise and better resolution of 3D motion. 3) Desktops are often left on and do not move. 4) The USB sensor is physically removed from the game, phone, or laptop, so human interaction with the device doesn’t reduce the sensors’ performance. 5) USB sensors can be aligned to North, so we know what direction the horizontal “X” and “Y” axes correspond to.

    If you are a science teacher at a K-12 school, please apply for a free USB sensor and accompanying QCN software. QCN has been able to purchase sensors to donate to schools in need. If you are interested in donating to the program or requesting a sensor, click here.

    BOINC is a leader in the field(s) of Distributed Computing, Grid Computing and Citizen Cyberscience.BOINC is more properly the Berkeley Open Infrastructure for Network Computing, developed at UC Berkeley.

    Earthquake safety is a responsibility shared by billions worldwide. The Quake-Catcher Network (QCN) provides software so that individuals can join together to improve earthquake monitoring, earthquake awareness, and the science of earthquakes. The Quake-Catcher Network (QCN) links existing networked laptops and desktops in hopes to form the worlds largest strong-motion seismic network.

    Below, the QCN Quake Catcher Network map
    QCN Quake Catcher Network map

    ShakeAlert: An Earthquake Early Warning System for the West Coast of the United States

    The U. S. Geological Survey (USGS) along with a coalition of State and university partners is developing and testing an earthquake early warning (EEW) system called ShakeAlert for the west coast of the United States. Long term funding must be secured before the system can begin sending general public notifications, however, some limited pilot projects are active and more are being developed. The USGS has set the goal of beginning limited public notifications in 2018.

    Watch a video describing how ShakeAlert works in English or Spanish.

    The primary project partners include:

    United States Geological Survey
    California Governor’s Office of Emergency Services (CalOES)
    California Geological Survey
    California Institute of Technology
    University of California Berkeley
    University of Washington
    University of Oregon
    Gordon and Betty Moore Foundation

    The Earthquake Threat

    Earthquakes pose a national challenge because more than 143 million Americans live in areas of significant seismic risk across 39 states. Most of our Nation’s earthquake risk is concentrated on the West Coast of the United States. The Federal Emergency Management Agency (FEMA) has estimated the average annualized loss from earthquakes, nationwide, to be $5.3 billion, with 77 percent of that figure ($4.1 billion) coming from California, Washington, and Oregon, and 66 percent ($3.5 billion) from California alone. In the next 30 years, California has a 99.7 percent chance of a magnitude 6.7 or larger earthquake and the Pacific Northwest has a 10 percent chance of a magnitude 8 to 9 megathrust earthquake on the Cascadia subduction zone.

    Part of the Solution

    Today, the technology exists to detect earthquakes, so quickly, that an alert can reach some areas before strong shaking arrives. The purpose of the ShakeAlert system is to identify and characterize an earthquake a few seconds after it begins, calculate the likely intensity of ground shaking that will result, and deliver warnings to people and infrastructure in harm’s way. This can be done by detecting the first energy to radiate from an earthquake, the P-wave energy, which rarely causes damage. Using P-wave information, we first estimate the location and the magnitude of the earthquake. Then, the anticipated ground shaking across the region to be affected is estimated and a warning is provided to local populations. The method can provide warning before the S-wave arrives, bringing the strong shaking that usually causes most of the damage.

    Studies of earthquake early warning methods in California have shown that the warning time would range from a few seconds to a few tens of seconds. ShakeAlert can give enough time to slow trains and taxiing planes, to prevent cars from entering bridges and tunnels, to move away from dangerous machines or chemicals in work environments and to take cover under a desk, or to automatically shut down and isolate industrial systems. Taking such actions before shaking starts can reduce damage and casualties during an earthquake. It can also prevent cascading failures in the aftermath of an event. For example, isolating utilities before shaking starts can reduce the number of fire initiations.

    System Goal

    The USGS will issue public warnings of potentially damaging earthquakes and provide warning parameter data to government agencies and private users on a region-by-region basis, as soon as the ShakeAlert system, its products, and its parametric data meet minimum quality and reliability standards in those geographic regions. The USGS has set the goal of beginning limited public notifications in 2018. Product availability will expand geographically via ANSS regional seismic networks, such that ShakeAlert products and warnings become available for all regions with dense seismic instrumentation.

    Current Status

    The West Coast ShakeAlert system is being developed by expanding and upgrading the infrastructure of regional seismic networks that are part of the Advanced National Seismic System (ANSS); the California Integrated Seismic Network (CISN) is made up of the Southern California Seismic Network, SCSN) and the Northern California Seismic System, NCSS and the Pacific Northwest Seismic Network (PNSN). This enables the USGS and ANSS to leverage their substantial investment in sensor networks, data telemetry systems, data processing centers, and software for earthquake monitoring activities residing in these network centers. The ShakeAlert system has been sending live alerts to “beta” users in California since January of 2012 and in the Pacific Northwest since February of 2015.

    In February of 2016 the USGS, along with its partners, rolled-out the next-generation ShakeAlert early warning test system in California joined by Oregon and Washington in April 2017. This West Coast-wide “production prototype” has been designed for redundant, reliable operations. The system includes geographically distributed servers, and allows for automatic fail-over if connection is lost.

    This next-generation system will not yet support public warnings but does allow selected early adopters to develop and deploy pilot implementations that take protective actions triggered by the ShakeAlert notifications in areas with sufficient sensor coverage.

    Authorities

    The USGS will develop and operate the ShakeAlert system, and issue public notifications under collaborative authorities with FEMA, as part of the National Earthquake Hazard Reduction Program, as enacted by the Earthquake Hazards Reduction Act of 1977, 42 U.S.C. §§ 7704 SEC. 2.

    For More Information

    Robert de Groot, ShakeAlert National Coordinator for Communication, Education, and Outreach
    rdegroot@usgs.gov
    626-583-7225

    Learn more about EEW Research

    ShakeAlert Fact Sheet

    ShakeAlert Implementation Plan


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 12:41 pm on December 14, 2019 Permalink | Reply
    Tags: "How Electrons Break the Speed Limit", Caltech, Charge transport near room temperature cannot be explained by standard models., In fact it violates the Planckian limit., In some materials the strong interaction between electrons and phonons in turn creates a new quasiparticle known as a polaron., Individual vibrations can be thought of as quasiparticles called phonons., , This advance is crucial since many semiconductors and oxides of interest for future electronics and energy applications exhibit polaron effects.   

    From Caltech: “How Electrons Break the Speed Limit” 

    Caltech Logo

    From Caltech

    1

    December 09, 2019
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    New understanding of charge transport reveals an exotic quantum mechanical regime.

    In work that may have broad implications for the development of new materials for electronics, Caltech scientists for the first time have developed a way to predict how electrons interacting strongly with atomic motions will flow through a complex material. To do so, they relied only on principles from quantum mechanics and developed an accurate new computational method.

    Studying a material called strontium titanate, postdoctoral researcher Jin-Jian Zhou and Marco Bernardi, assistant professor of applied physics and materials science, showed that charge transport near room temperature cannot be explained by standard models. In fact, it violates the Planckian limit, a quantum speed limit for how fast electrons can dissipate energy while they flow through a material at a given temperature.

    Their work was published in the journal Physical Review Research on December 2.

    The standard picture of charge transport is simple: electrons flowing through a solid material do not move unimpeded but instead can be knocked off course by the thermal vibrations of atoms that make up the material’s crystalline lattice. As the temperature of a material changes, so too does the amount of vibration and the resulting effect of this vibration on charge transport.

    Individual vibrations can be thought of as quasiparticles called phonons, which are excitations in materials that behave like individual particles, moving and bouncing around like an object. Phonons behave like the waves in the ocean, while electrons are like a boat sailing across that ocean, jostled by the waves. In some materials, the strong interaction between electrons and phonons in turn creates a new quasiparticle known as a polaron.

    “The so-called polaron regime, in which electrons interact strongly with atomic motions, has been out of reach for first-principles calculations of charge transport because it requires going beyond simple perturbative approaches to treat the strong electron-phonon interaction,” says Bernardi. “Using a new method, we have been able to predict both the formation and the dynamics of polarons in strontium titanate. This advance is crucial since many semiconductors and oxides of interest for future electronics and energy applications exhibit polaron effects.”

    Strontium titanate is known as a complex material because at different temperatures its atomic structure changes dramatically, with the crystal lattice shifting from one shape to another, which in turn shifts the phonons that electrons have to navigate. Last year, Zhou and Bernardi showed in a Physical Review Letters paper that they can describe the phonons associated with these structural phase transitions and include them in their computational workflow to accurately predict the temperature dependence of the electron mobility in strontium titanate.

    Now, they have developed a new method that can describe the strong interactions between the electrons and phonons in strontium titanate. This allows them to explain the formation of polarons and accurately predict both the absolute value and the temperature dependence of the electron mobility, a key charge-transport property in materials.

    In doing so, they uncovered an exotic feature of strontium titanate: charge transport near room temperature cannot be explained with the simple standard picture of electrons scattering with atomic vibrations in the material. Rather, transport occurs in a subtle quantum mechanical regime in which the electrons carry electricity collectively rather than individually, allowing them to violate the theoretical limit for charge transport.

    “In strontium titanate, the usual mechanism of charge transport due to electrons scattering with phonons has been widely accepted for the last half century. However, the picture that emerges from our study is far more complicated,” says Zhou. “At room temperature, it’s as if roughly half of each electron contributes to charge transport through the usual phonon scattering mechanism, while the other half of the electron contributes to a collective form of transport that is not yet fully understood.”

    In addition to representing a fundamental advance in the understanding of charge transport, the new method by Zhou and Bernardi can be applied to many semiconductors as well as to materials such as oxides and perovskites, and to new quantum materials exhibiting polaron effects. Besides charge transport, Zhou and Bernardi plan to investigate materials with unconventional thermoelectricity (the generation of electricity from heat) and superconductivity (electric current without resistance). In these materials, existing calculations have not yet been able to take into account polaron effects.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 10:30 am on December 5, 2019 Permalink | Reply
    Tags: "Caltech Undergrads Build Robot for DARPA Challenge", Balto competed in the August 2019 tunnel-navigation section of the DARPA SubT Challenge., Balto is about half the size of the more powerful Huskies and costs an order of magnitude less., Balto-the robot truck, Caltech, , Like other teams CoSTAR has a diverse fleet of different types of robots including a hybrid rolling/flying robot; a tracked tank-like robot; and small flying drones that can navigate tunnels., Team CoSTAR, Truck-like robot will be a probe for exploring underground arenas.   

    From Caltech: “Caltech Undergrads Build Robot for DARPA Challenge” 

    Caltech Logo

    From Caltech

    December 02, 2019
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    Truck-like robot will be a probe for exploring underground arenas.

    1
    Caltech seniors Jake Ketchum and Alexandra (Sasha) Bodrova work on the superstructure that holds Balto’s critical custom components.

    A robot designed and built by undergraduate students at Caltech working with graduate students at Caltech and JPL, which Caltech manages for NASA, took to the field in the first phase of the Defense Advanced Research Projects Agency (DARPA) Subterranean (SubT) Challenge this summer, where the Caltech-JPL team took second place.

    The SubT Challenge is an international competition sponsored by DARPA to advance technologies to autonomously map, navigate, and search underground environments. Teams earn points by accurately identifying and mapping artifacts that represent items a first responder might find underground: items like a cell phone, backpack, or even a thermal manikin that simulates a survivor.

    The August competition, a tunnel-navigation task, was the first of three stages leading up to a final event in August 2021. In the second stage, to be held in Februrary 2020, the team will compete in an urban underground environment; in the third, in August 2020, they move to a cave. Teams that fail to perform well enough in any stage can be disqualified. For the final, the remaining teams will compete in an event that combines all three environments.

    3
    Balto competed in the August 2019 tunnel-navigation section of the DARPA SubT Challenge.

    In the tunnel competition, there were 11 teams, most made up of consortia of research institutions and private companies. Team CoSTAR (Collaborative SubTerranean Autonomous Resilient Robots), led by JPL Robotics Technologist Ali Agha, includes JPL, Caltech, MIT, the Korea Advanced Institute of Science and Technology (KAIST), and Sweden’s Lulea University of Technology.

    Like other teams, CoSTAR has a diverse fleet of different types of robots, including a hybrid rolling/flying robot, a tracked tank-like robot, and small flying drones that can navigate tunnels. The vehicles work together to perform assigned tasks: for example, a ground robot might begin exploration but come to an unnavigable roadblock, at which point a flying drone might be called in to explore beyond the roadblock. The backbone of the CoSTAR fleet is a group of simple, efficient, and reliable truck-like four-wheeled robots called the Huskies.

    The newest addition to the fleet, added this summer, looks like the runt of the Husky litter. Dubbed Balto after a famous rescue sled dog, the new robot was built atop a commercial radio control car. Caltech’s Joel Burdick, the Richard L. and Dorothy M. Hayman Professor of Mechanical Engineering and Bioengineering and JPL research scientist, and the leader of the Caltech section of the CoSTAR team, decided that using an off-the-shelf R/C as a base would fast track the development of Balto since the team was able to start with a vehicle that already had a sturdy suspension and powerful electric motor.

    Balto is about half the size of the more powerful Huskies, and costs an order of magnitude less. The final product is a vehicle that is about a meter long, weighs about 12 kilograms, and is capable of navigating slopes of up to 40 degrees. Because it is so light, it is also a good deal faster than the Huskies, and can reach speeds of 55 miles per hour.

    “The idea was to create a ground-based scout,” Burdick says. “The drones are our air-based scouts, and Balto is our eyes and ears on the ground. It’s light, cheap, and fast. It can get in, find out what’s going on, and help us to make decisions about how to proceed.” Balto can also fill in as a substitute in emergencies. For example, since wireless signals are often blocked in underground environments, SubT competitors have had to build ad hoc wireless networks by using robots stationed along the tunnel as wireless nodes so that the robots can communicate with one another. If one of the nodes fails, Balto is capable or quickly rushing in to fill in the gap.

    Initial work on Balto began in CS/EE/ME 75, Multidisciplinary Systems Engineering, a cross-discipline special projects undergraduate class at Caltech. This spring, a team of about a half-dozen undergraduate students began work on the off-the-shelf car that would become Balto. First, they stripped the body off of the vehicle’s chassis and began designing a removable superstructure that would house all of the equipment necessary to transform an R/C car into a self-guided robot explorer. The superstructure of Balto, which was built using milling machines and 3-D printers at Caltech, can be lifted as a single unit off of the chassis. Balto features a towering LIDAR unit (a detection and ranging technology in which the vehicle’s surroundings scanned with laser beams) that works in tandem with twin cameras to “see” its surroundings, a radio receiver that allows it to communicate with the rest of the fleet, and an on-board computer that contains the programming that makes the vehicle autonomous.

    “The chassis is largely stock, but Balto’s electrical and control systems have been entirely replaced,” says Jake Ketchum, now a Caltech senior, who led the CS/EE/ME 75 class team and continued to work on Balto through the Summer Undergraduate Research Fellowship (SURF) program.

    The team also swapped out the vehicle’s simple motor controller to an upgraded version that gives the autonomous guidance system more precise control over the vehicle’s speed, which allows them to more accurately place Balto where it is needed.

    “Balto was tested in the field and, in the fully autonomous mode, successfully navigated tunnels that were more than 100 meters long,” says Alexandra (Sasha) Bodrova, now a Caltech senior who also worked on Balto through the SURF program. “Balto detected and avoided obstacles such as rocks and rails, made sharp turns, and then returned to the starting line, in reverse.”

    4
    Alexandra Bodrova fabricates custom parts for Balto.

    At the beginning of the summer, the Balto team was expanded to include graduate student researchers Nikhilesh Alatur and Anushri Dixit, who were tasked with incorporating autonomous control to the vehicle and integrating it into CoSTAR’s fleet.

    Alatur and Dixit were among the CoSTAR team members who traveled to Pittsburgh for the first leg of the SubT Challenge, held at the National Institute for Occupational Safety and Health (NIOSH) Mining Program’s Safety Research Coal Mine and Experimental Mine, a federal site where mine-related safety and health research is conducted.

    The competition took place over the course of four days, with each team given one hour per day to complete specific tasks, most of which involved finding and engaging with objects of interest, like a backpack or a lever arm. While a small group of 10 engineers launched the robots at the mouth of the mine, most of the rest of the team, including Alatur and Dixit, watched the action via a livestream from the conference room near the mine.

    “Everyone worked in shifts, fixing robots during the night and watching the competition or sleeping during the day,” Dixit says.

    “Every day, up to 20 minutes before the start of our run, we weren’t even sure the team was going to get off of the line,” Burdick says, describing how the team would scramble to address software and hardware issues on its completely custom robots.

    Given the importance of the Huskies to the fleet, the first order of business was always to make sure they made it into the field. For the first three days of the competition, Balto mainly warmed the bench as the team deployed its other vehicles.

    Then, on the fourth and final day of competition, the decision was made to send in Balto.

    “It was pretty intense. There were five or six people gathered around the screen, and as soon as Balto went in, everyone started screaming and shouting and cheering,” says Alatur, graduate student at ETH Zurich who is spending a six-month stint on the CoSTAR team as a student researcher at JPL. “We were happy to see that Balto was sent in for the last few minutes of the competition and could make its debut in a DARPA challenge.” During the competition, Alatur and Dixit stayed in constant text contact with Ketchum and Bodrova, who watched the livesteam from Caltech and were equally excited to see the robot take to the field.

    Balto’s mission was limited; as Burdick puts it, the main goal was to see how the robot performed and to gather data that can be used to improve it for the next round of the competition. The original plan was that Balto would be tasked with positioning communication nodes—basically, wifi signal boosters that enable all of the robots in the tunnel to stay connected—but it turned out to be unnecessary. Instead, Balto drove 125 meters into the tunnel and stopped, just as directed, and acted as a wifi unit to relay signals as necessary. “In the end, we didn’t truly need it, but it did its job well,” Burdick says. “And more importantly, we gained data about Balto’s performance that will help us down the line.”

    Because of Balto’s speed, diminutive size, and ruggedness, Burdick predicts a growing role for the little robot in future competitions. This year’s CS/EE/ME 75 class will continue to refine Balto, as well as other new vehicles to be used in the next phases of the competition in February and August, 2020.

    “I think we’re going to be grateful to have a small, tough robots like Balto when we get to the final event in 2021,” he says.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 11:06 am on November 21, 2019 Permalink | Reply
    Tags: "Caltech and the City of Pasadena Team Up to Build Seismic Sensing Network", A citywide fiber optic earthquake detector capable of mapping how temblors are shaking the city at millimeter-scale resolution., Caltech   

    From Caltech: “Caltech and the City of Pasadena Team Up to Build Seismic Sensing Network” 

    Caltech Logo

    From Caltech

    1

    November 19, 2019
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    Caltech and the City of Pasadena are teaming up to create a citywide fiber optic earthquake detector capable of mapping how temblors are shaking the city at millimeter-scale resolution.

    The work will take advantage of two currently unused—or “dark”—strands of Pasadena’s fiber optic cable that stretch in a large loop around the city. Using a couple strands of fiber to measure seismic activity will gather data equivalent to more than 30,000 seismometers, while only 11 traditional seismometers exist within the city limits today. Zhongwen Zhan, assistant professor of geophysics, will tap into the fiber network at the Seeley G. Mudd Building of Geophysics and Planetary Science on Caltech’s campus on California Boulevard.

    2

    There, Zhan will station two laser emitters that shoot beams of light through the cables. The cables have tiny imperfections every few meters that reflect back a minuscule portion of the light to the source, where it is tracked and recorded. In this manner, each imperfection acts as a trackable waypoint along the fiber optic cable, which is typically buried just below ground level. Seismic waves moving through the ground cause the cable to expand and contract slightly, which changes the travel time of light to and from these waypoints. Thus, the imperfections act like individual seismometers that allow seismologists to observe the motion of seismic waves.

    “Engineers try to minimize the imperfections in the cable because it adds noise when transmitting information from one point to another. For us, however, the imperfections are the point. They turn the cable into a big chain of virtual seismometers,” Zhan says.

    The laser light launched into the fiber is emitted by distributed acoustic sensing (DAS) interrogators, devices designed for use in oil exploration. One, designed in the lab of Miguel Gonzalez-Herraez of the University of Alcalá in Spain and constructed by manufacturer Aragon Photonics, will track a 37-kilometer section of cable clockwise from Caltech’s campus. The other, borrowed from manufacturer OptaSense, was deployed to monitor a section of fiber along the 395 Freeway, tracking aftershocks from this summer’s Ridgecrest earthquake sequence. It recently returned to Pasadena to take a more detailed look at a 10-kilometer section along the same cable path, but counter-clock-wise from the Caltech campus.

    The unbroken loop of cable allows for light to be shot in both directions through the cable, generating a clearer signal. Ultimately, the DAS devices should capture 20 terabytes of data every month. Because of the high resolution of data that the fiber can capture, the network could one day provide city officials real-time information during an earthquake about how severe the shaking is throughout the city on a block-by-block basis.

    The city maintains a network of fiber optic cable running beneath Pasadena for municipal operations and commercial services, not all of which is currently in use. City officials granted access to that dark fiber to Zhan under a five-year agreement.

    “The City of Pasadena’s fiber optics paired with Caltech’s research will produce a tremendous amount of data that will help our efforts to prepare, educate, and communicate the impacts of earthquakes in our community,” says Phillip Leclair, chief information officer for the City of Pasadena. “Measuring seismic activity with fiber will give officials impact and damage predictions by neighborhood—a huge benefit for public safety and disaster recovery.”

    Zhan hopes that this project can serve as a model for other cities and seismologists, with municipalities throughout Southern California taking advantage of their fiber optic networks for seismic monitoring.

    “These fiber optic networks already exist in many municipalities, creating the opportunity for this project to expand throughout the region and perhaps even beyond,” Zhan says.

    “The Pasadena project is an important step forward in lighting up dark fiber throughout Southern California and achieving our vision of a seismic monitoring system equivalent to having a million seismometers placed throughout the region,” says Mike Gurnis, director of Caltech’s Seismological Laboratory and John E. and Hazel S. Smits Professor of Geophysics. “This will be a leap forward in our ability to monitor the subsurface in much greater detail. We are particularly grateful for the support shown by the City of Pasadena. This advancement would never have happened without them.”

    The work is made possible by a National Science Foundation CAREER Award, funding from Caltech trustee Li Lu, and a partnership with the City of Pasadena, and Caltech’s Division of Geological and Planetary Sciences.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 3:23 pm on November 13, 2019 Permalink | Reply
    Tags: , Caltech, , IEQNET-Illinois Express Quantum Network,   

    From Fermi National Accelerator Lab: “DOE awards Fermilab and partners $3.2 million for Illinois quantum network” 

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    From Fermi National Accelerator Lab , an enduring source of strength for the US contribution to scientific research world wide.

    November 13, 2019
    edited by Leah Hesla

    1
    The proposed Illinois Express Quantum Network is a metropolitan-scale, quantum-classical hybrid design combining quantum technologies with existing classical networks to create a multinode system for multiple users.

    The Department of Energy has announced that it will grant Fermilab and partner institutions $3.2 million to develop designs for transparent optical quantum networks and demonstrate their operation in the greater Chicago area.

    The proposed Illinois-Express Quantum Network, or IEQNET, connects nodes at Fermilab and proposed nodes at Northwestern University’s Chicago and Evanston campuses. The metropolitan-scale network uses a combination of cutting-edge quantum and classical technologies to transmit quantum information and will be designed to coexist with classical networks.

    “Our team brings together researchers who are leading the way in quantum communications, classical networking, quantum devices and fast-timing electronics,” said scientist Panagiotis Spentzouris, head of quantum science at Fermilab and the project’s principal investigator. “That marriage of world-class expertise enables us to develop the new network.”

    Fermilab is the lead institution for the IEQNET collaboration, which includes the Department of Energy’s Argonne National Laboratory, Caltech and Northwestern University.

    “We have leading quantum technology capabilities at our respective institutions,” said Northwestern University’s Prem Kumar, one of the researchers on the project. “Now we’re combining them to create new opportunities for distributed quantum communications.”

    Scientists have previously demonstrated point-to-point quantum communications over short distances — on the order of 10 miles — in fiber-optic cables. IEQNET’s goal is to demonstrate a multinode fiber-optic quantum network that supports multiple users.

    “We will be using state-of-the-art sources and photodetectors in nodes we have built already at Fermilab to co-distribute classical and quantum information across Chicagoland,” said Caltech scientist Maria Spiropulu, another IEQNET researcher. “We want to identify and address the challenges toward nontrivial, long-distance multilayered architectures that support multiple end-users and test various protocols.”

    IEQNET’s objective supports the United States in meeting the goals of its National Quantum Initiative, a coordinated multiagency program to support research and training in quantum information science. It also positions Chicago as one of the few places in the nation advancing quantum communications. The proposed network stretches between the Chicago area institutions using existing fiber-optic cables.

    “We want to utilize existing links because we have significant infrastructure that has already been laid for classical communications,” said Rajkumar Kettimuthu, an Argonne scientist affiliated with IEQNET. “One of the challenges will be to achieve classical and quantum co-existence in the same fibers.”

    IEQNET leverages existing conventional infrastructure and experience from ESnet, a high-speed computer network serving DOE scientists and their collaborators worldwide. ESnet is managed by Lawrence Berkeley National Laboratory, also a DOE national laboratory.

    The project also brings together small quantum tech industry partners, including businesses such as NuCrypt and HyperLight, and the Intelligent Quantum Networks and Technologies, or INQNET, program, which was developed through a Caltech and AT&T partnership and is a member of the Quantum Economic Development Consortium of the National Institute of Standards and Technology.

    By connecting business with academia, IEQNET has the potential to generate new technologies that have wider application in industry, helping elevate the Chicago area as a hot spot for technology transfer in quantum science.

    IEQNET is one of the recently announced five four-year projects aimed at developing wide-area quantum networks funded by the DOE Office of Science.

    “We are on the threshold of a new era in quantum information science and quantum computing and networking, with potentially great promise for science and society,” said DOE Under Secretary for Science Paul Dabbar in an announcement from DOE. “These projects will help ensure U.S. leadership in these important new areas of science and technology.”

    See the full here.


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    FNAL Icon

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 1:00 pm on November 7, 2019 Permalink | Reply
    Tags: "Unlocking Turbulence", , Caltech,   

    From Caltech: “Unlocking Turbulence” 

    Caltech Logo

    From Caltech

    November 05, 2019
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    Caltech engineer exploits the repeating structure of turbulence to create a more complete model of the phenomenon.

    A Caltech engineer has unlocked some of the secrets behind turbulence, a much-studied but difficult-to-pin-down phenomenon that mixes fluids when they flow past a solid boundary.

    Beverly McKeon, the Theodore von Kármán Professor of Aeronautics in the Division of Engineering and Applied Science, studies fluid mechanics.

    1
    Beverly McKeon

    She specializes in turbulent flows, or technically speaking those with high Reynolds numbers. These types of flows are often seen in pipes and around aircraft and are of keen interest, for example, to aerospace engineers.

    1
    Turbulence. McKeon Research Group at Caltech.

    At the boundary where a fluid flows over a fixed structure, a turbulent boundary layer is created where the fluid interacts with the wall, creating eddies in the current. These eddies may seem to be random on first glance, but they actually create distinct patterns, with countless tiny eddies close to the wall; fewer but larger eddies located a little farther out; and even fewer, but still larger, eddies beyond those. These eddies have a significant impact on the fluid flow, helping to determine features such as its pressure, velocity, and density, which are important to understand when engineering an aircraft or industrial piping, for example.

    In the 1950s and ’60s, mathematician Alan Townsend of Cambridge University proposed that a lot of the important statistical properties of a turbulent flow could be described based on this concept of eddies as persistent, organized flow patterns that are, in essence, “attached” to a wall—even without a clear understanding of what those eddies actually are. Through the ’80s and ’90s, researchers led by Tony Perry, Ivan Marusic, and their colleagues at Australia’s University of Melbourne built on Townsend’s hypothesis to develop the “attached eddy” model of wall turbulence, which has proven to be effective at describing the statistical behavior of the common phenomenon.

    As an analogy, think of weather prediction. If you compiled 100 years’ worth of weather reports, you could derive the average weather for an area and make a reasonable prediction about what the weather will be tomorrow. That is a statistical model. If you instead studied each of the physical systems that affect the weather—the ocean, the clouds, the topography—you could create a model that predicts the weather based on the various inputs to that system. That is a dynamical model.

    A statistical model is easier to process, but a dynamical model is not a slave to the past; because it attempts to describe and understand what drives the system overall, it is capable of predicting future changes in the system that might be outside of the average norms. And like the weather, turbulence is a dynamic and ever-changing phenomenon.

    The problem, however, is that simulating something as complex as turbulence using the equations of motion is an incredibly complex, computationally challenging task, McKeon says. Imagine trying to disassemble an entire car with just a monkey wrench. You might eventually get the job done, but it will take a lot of time and energy.

    McKeon found a way to bridge the empirical and mathematical models by creating an equations-derived description of turbulence that exploits the fact that turbulence creates predictably repeating structures. The shape and structure of the eddies in turbulence are geometrically self-similar, meaning that each of the eddies are identical, just on different scales, similar to a fractal pattern.

    Mathematically quantifying these repetitions, McKeon was able to formulate a dynamical model that describes turbulence using a sort of shorthand, allowing it to extrapolate how the overall system will look based on a zoomed-in look at just a few eddies. Because it describes an incredibly large-scale and complex system by boiling it down to a simple, repeating component, McKeon’s model can generate mathematically useful models of turbulent systems using dramatically less compute power than was previously required.

    “We knew that, underlying these very complicated structures, there had to be a very simple pattern. We just didn’t know what that pattern was until now,” says McKeon, who next plans to dig deeper into the model to quantify just how many eddies should be included to create an accurate representation of the whole.

    The model could prove useful to engineers across industry who are looking to more easily simulate turbulent systems. But more importantly, it represents fundamental research that will help scientists and engineers better understand what drives those turbulent systems.

    McKeon’s study is titled “Self-similar hierarchies and attached eddies” and was published by Physical Review Fluids on August 26. Her work was funded by the Office of Naval Research.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
  • richardmitnick 2:05 pm on October 23, 2019 Permalink | Reply
    Tags: "Earthquakes in Slow Motion", , Caltech, , So-called "slow slip" or "silent" earthquakes   

    From Caltech: “Earthquakes in Slow Motion” 

    Caltech Logo

    From Caltech

    October 23, 2019
    Robert Perkins
    (626) 395‑1862
    rperkins@caltech.edu

    Studying “slow-slip” events could shed light on destructive temblors.

    1

    A new study from Caltech finds that so-called “slow slip” or “silent” earthquakes behave more like regular earthquakes than previously thought. The discovery opens the door for geoscientists to use these frequent and nondestructive events as an easy-to-study analog that will help them find out what makes earthquakes tick.


    GPS stations reveal activity beneath Cascadia where the oceanic floor slides beneath North America. The plate interface is locked at shallow depths (the shaded area), but we see recurring slow-slip events (in blue) that unzip the plate interface, generating tremors (the black dots).

    Slow-slip events were first noted about two decades ago by geoscientists tracking otherwise imperceptible shifts in the earth using GPS technology. They occur when faults grind incredibly slowly against each other, like an earthquake in slow motion. For example, a slow-slip event that occurs over the course of weeks might release the same amount of energy as a minute-long magnitude-7.0 earthquake. Because they occur deep in the earth and release energy so slowly, there is very little deformation at the surface, although the slow events might affect an area of thousands of square kilometers. As such, they were only noted when GPS technology was refined to the point that it could track those very minute shifts. Slow-slip events also do not occur along every fault; so far, they have been spotted in just a handful of locations including the Pacific Northwest, Japan, Mexico, and New Zealand.

    As they have only just begun to be detected and cataloged, a lot remains unknown about them, says Jean-Philippe Avouac, Caltech’s Earle C. Anthony Professor of Geology and Mechanical and Civil Engineering. “There’s a lot of uncertainty. You can’t study them using traditional seismological techniques because the signal they create is too faint and gets lost in the noise from human activities as well as from natural geological processes like ocean waves, rivers, and winds.” Before Avouac’s group began this study, there were not enough documented slow-slip events to determine their scaling properties reliably, he says.

    Avouac’s group designed and applied an innovative signal processing technique to detect and image the slow-slip events along Washington state’s Cascadia Subduction Zone, where the North American tectonic plate is sliding southwest over the Pacific Ocean plate, using a network of 352 GPS stations. The researchers analyzed data spanning the years 2007 to 2018 and were able to build a catalog of more than 40 slow-slip events of varied sizes. Their findings appear in Nature on October 23.

    Compiling data from these events, the researchers were able to characterize the features of slow-slip events more precisely than previously possible. One key finding from the study is that slow-slip events obey the same scaling laws as regular earthquakes.

    In this context, the scaling law describes the “moment” of a slip event on a fault—which quantifies the elastic energy released by slip on a fault—as a function of the duration of slip. In practical terms, that means that a big slip across a broad area yields a long-lasting earthquake. It has long been known that the moment of an earthquake is proportional to the cube of the amount of time the earthquake lasts. In 2007, a team from the University of Tokyo and Stanford suggested that slow-slip events appear to be different, with the moment seemingly directly proportional to time.

    Armed with their new fleshed-out catalog, Avouac’s team argues that the magnitudes of slow-slip events also are proportional to the cube of their duration, just like regular earthquakes.

    Since these events behave similarly to regular earthquakes, studying them could shed light on their more destructive cousins, Avouac says, particularly because slow-slip events occur more frequently. While a traditional magnitude-7.0 earthquake might only occur along a fault every couple of hundred years, a slow-slip event of that magnitude can reoccur along the same fault every year or two.

    “If we study a fault for a dozen years, we might see 10 of these events,” Avouac says. “That lets us test models of the seismic cycle, learning how different segments of a fault interact with one another. It gives us a clearer picture of how energy builds up and is released with time along a major fault.” Such information could offer more insight into earthquake mechanics and the physics governing their timing and magnitude, he says.

    Avouac’s co-authors are Sylvain Michel of the École normale supérieure in Paris and Caltech visiting researcher Adriano Gualandi. Their work was funded by the National Science Foundation and the French National Centre for Space Studies.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings
    Please help promote STEM in your local schools.


    Stem Education Coalition

    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”

    Caltech campus

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel