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Computer Modeling

Unveiling New Disturbances in Hypersonic Flows

At hypersonic speeds, complexities occur when the gases interact with the surface of the vehicle such as boundary layers and shock waves. Researchers were able to observe new disturbances in simulations conducted for the first time in 3D.

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As researchers delve into the complex world of hypersonic speeds, they encounter unexpected phenomena when gases interact with the surface of vehicles. A team from the University of Illinois Urbana-Champaign’s Department of Aerospace Engineering has made a groundbreaking discovery by conducting fully 3D simulations for the first time. This achievement was possible due to access to Frontera, the National Science Foundation-funded leadership-class computer system, and software developed by previous graduate students.

The researchers, Deborah Levin and Irmak Taylan Karpuzcu, observed new disturbances in the flow around a cone-shaped model at hypersonic speeds. Normally, one would expect concentric ribbons of gas around the cone, but they noticed breaks in the flow within shock layers both in single and double cone shapes. These breaks were particularly noticeable near the tip of the cone, where air molecules are closer together, making them more viscous.

The team’s findings indicate that as the Mach number increases, the shock wave gets closer to the surface, promoting these instabilities. However, when they ran simulations at lower speeds (Mach 6), they did not see the break in the flow. This suggests that the cone geometry, which represents a simplified version of many hypersonic vehicles, plays a crucial role in understanding how the flow affects surface properties.

The researchers’ software allowed them to run the simulation efficiently on parallel processors, making it much faster than previous methods. They were able to compare their results with data from experiments under high-speed conditions and found breaks that they didn’t expect to see. The most challenging part of the work was analyzing why these breaks in the flow were happening.

The team developed a code based on triple-deck theory to numerically simulate the problem again. Running the 3D direct simulation Monte Carlo simulation is hard, but when they set up a second computer program to make sure everything works and is within the limits for their flow conditions, they saw the break in two big chunks in 180-degree periodicity around the cone.

The beauty of the direct simulation Monte Carlo lies in its ability to track each air molecule in the flow and capture shocks. This method introduces randomness and repetition to calculate fluid dynamics, making it more extensive than classical computational fluid dynamics methods.

This research has significant implications for designing hypersonic vehicles, as understanding how the flow affects surface properties can lead to better design considerations. The team’s findings also demonstrate the importance of conducting fully 3D simulations in researching complex phenomena at high speeds.

Computational Biology

A Quantum Leap Forward – New Amplifier Boosts Efficiency of Quantum Computers 10x

Chalmers engineers built a pulse-driven qubit amplifier that’s ten times more efficient, stays cool, and safeguards quantum states—key for bigger, better quantum machines.

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Quantum computers have long been touted as revolutionary machines capable of solving complex problems that stymie conventional supercomputers. However, their full potential has been hindered by the limitations of qubit amplifiers – essential components required to read and interpret quantum information. Researchers at Chalmers University of Technology in Sweden have taken a significant step forward with the development of an ultra-efficient amplifier that reduces power consumption by 90%, paving the way for more powerful quantum computers with enhanced performance.

The new amplifier is pulse-operated, meaning it’s activated only when needed to amplify qubit signals, minimizing heat generation and decoherence. This innovation has far-reaching implications for scaling up quantum computers, as larger systems require more amplifiers, leading to increased power consumption and decreased accuracy. The Chalmers team’s breakthrough offers a solution to this challenge, enabling the development of more accurate readout systems for future generations of quantum computers.

One of the key challenges in developing pulse-operated amplifiers is ensuring they respond quickly enough to keep pace with qubit readout. To address this, the researchers employed genetic programming to develop a smart control system that enables rapid response times – just 35 nanoseconds. This achievement has significant implications for the future of quantum computing, as it paves the way for more accurate and powerful calculations.

The new amplifier was developed in collaboration with industry partners Low Noise Factory AB and utilizes the expertise of researchers at Chalmers’ Terahertz and Millimeter Wave Technology Laboratory. The study, published in IEEE Transactions on Microwave Theory and Techniques, demonstrates a novel approach to developing ultra-efficient amplifiers for qubit readout and offers promising prospects for future research.

In conclusion, the development of this highly efficient amplifier represents a significant leap forward for quantum computing. By reducing power consumption by 90%, researchers have opened doors to more powerful and accurate calculations, unlocking new possibilities in fields such as drug development, encryption, AI, and logistics. As the field continues to evolve, it will be exciting to see how this innovation shapes the future of quantum computing.

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Artificial Intelligence

AI Uncovers Hidden Heart Risks in CT Scans: A Game-Changer for Cardiovascular Care

What if your old chest scans—taken years ago for something unrelated—held a secret warning about your heart? A new AI tool called AI-CAC, developed by Mass General Brigham and the VA, can now comb through routine CT scans to detect hidden signs of heart disease before symptoms strike.

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The Massachusetts General Brigham researchers have developed an innovative artificial intelligence (AI) tool called AI-CAC to analyze previously collected CT scans and identify individuals with high coronary artery calcium (CAC) levels, indicating a greater risk for cardiovascular events. Their research, published in NEJM AI, demonstrated the high accuracy and predictive value of AI-CAC for future heart attacks and 10-year mortality.

Millions of chest CT scans are taken each year, often in healthy people, to screen for lung cancer or other conditions. However, this study reveals that these scans can also provide valuable information about cardiovascular risk, which has been going unnoticed. The researchers found that AI-CAC had a high accuracy rate (89.4%) at determining whether a scan contained CAC or not.

The gold standard for quantifying CAC uses “gated” CT scans, synchronized to the heartbeat to reduce motion during the scan. However, most chest CT scans obtained for routine clinical purposes are “nongated.” The researchers developed AI-CAC, a deep learning algorithm, to probe through these nongated scans and quantify CAC.

The AI-CAC model was 87.3% accurate at determining whether the score was higher or lower than 100, indicating a moderate cardiovascular risk. Importantly, AI-CAC was also predictive of 10-year all-cause mortality, with those having a CAC score over 400 having a 3.49 times higher risk of death over a 10-year period.

The researchers hope to conduct future studies in the general population and test whether the tool can assess the impact of lipid-lowering medications on CAC scores. This could lead to the implementation of AI-CAC in clinical practice, enabling physicians to engage with patients earlier, before their heart disease advances to a cardiac event.

As Dr. Raffi Hagopian, first author and cardiologist at the VA Long Beach Healthcare System, emphasized, “Using AI for tasks like CAC detection can help shift medicine from a reactive approach to the proactive prevention of disease, reducing long-term morbidity, mortality, and healthcare costs.”

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Computer Modeling

Harnessing True Randomness from Entangled Photons: The Colorado University Randomness Beacon (CURBy)

Scientists at NIST and the University of Colorado Boulder have created CURBy, a cutting-edge quantum randomness beacon that draws on the intrinsic unpredictability of quantum entanglement to produce true random numbers. Unlike traditional methods, CURBy is traceable, transparent, and verifiable thanks to quantum physics and blockchain-like protocols. This breakthrough has real-world applications ranging from cybersecurity to public lotteries—and it’s open source, inviting the world to use and build upon it.

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The Colorado University Randomness Beacon (CURBy) is a pioneering service that harnesses the true randomness of entangled photons to produce unguessable strings of numbers. This breakthrough was made possible by the work of scientists at the National Institute of Standards and Technology (NIST) and their colleagues at the University of Colorado Boulder.

“True randomness is something that nothing in the universe can predict in advance,” said Krister Shalm, a physicist at NIST. “If God does play dice with the universe, then you can turn that into the best random number generator that the universe allows.”

The CURBy system uses a Bell test to measure pairs of entangled photons whose properties are correlated even when separated by vast distances. When researchers measure an individual particle, the outcome is random, but the properties of the pair are more correlated than classical physics allows, enabling researchers to verify the randomness.

This is the first random number generator service to use quantum nonlocality as a source of its numbers, and the most transparent source of random numbers to date. The results are certifiable and traceable to a greater extent than ever before.

The CURBy system consists of a nonlinear crystal that generates entangled photons, which travel via optical fiber to separate labs at opposite ends of the hall. Once the photons reach the labs, their polarizations are measured. The outcomes of these measurements are truly random.

NIST passes millions of these quantum coin flips to a computer program at the University of Colorado Boulder, where special processing steps and strict protocols are used to turn the outcomes into 512 random bits of binary code (0s and 1s). The result is a set of random bits that no one, not even Einstein, could have predicted.

The CURBy system has been operational for several months now, with an impressive success rate of over 99.7%. The ability to verify the data behind each random number was made possible by the Twine protocol, a novel set of quantum-compatible blockchain technologies developed by NIST and its collaborators.

“The Twine protocol lets us weave together all these other beacons into a tapestry of trust,” said Jasper Palfree, a research assistant on the project at the University of Colorado Boulder. This allows any user to verify the data behind each random number, providing security and traceability.

The CURBy system can be used anywhere an independent, public source of random numbers would be useful, such as selecting jury candidates, making a random selection for an audit, or assigning resources through a public lottery.

“I wanted to build something that is useful. It’s this cool thing that is the cutting edge of fundamental science,” said Gautam Kavuri, a graduate student on the project. The whole process is open source and available to the public, allowing anyone to not only check their work but even build on the beacon to create their own random number generator.

The CURBy system has the potential to revolutionize fields such as cryptography, gaming, and finance, where true randomness is essential. By harnessing the power of entangled photons, scientists have created a truly independent source of random numbers that can be trusted.

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