Bound states in the continuum is possible in the acoustoelastic coupling
2023-07-12
(Press-News.org)
Let’s imagine a hypothetical scenario where two individuals are gripping a rope, each holding one end. Person A proceeds to shake the rope in an up-and-down motion, thus generating a propagating wave that travels towards person B. Now, if person C, positioned between person A and B, engages in a comparable frequency of waving motion as that of the rope’s wave, could the wave be redirected back to person A rather than reaching person B? Initially, this situation appears implausible, as person C does not physically interact with the rope held by person A and B, seemingly defying the possibility of achieving a 100% wave reflection similar to that observed in a perfect mirror. Nonetheless, this phenomenon finds explanation within the domain of physics and is known as the “bound state in the continuum (BIC)”.
The study of BIC has encompassed diverse disciplines including quantum mechanics, optics, semi-conductors, and nano-optics. Utilizing this phenomenon facilitates the confinement of light particles, or photons, preventing their forward propagation. Moreover, BIC holds promise for the development of highly sensitive sensors. Previous research into BIC has predominantly focused on microscale and nanoscale contexts while investigations using visible structures to explain this phenomenon have been absent.
Recently, a research team led by Professor Junsuk Rho from the Department of Mechanical Engineering and the Department of Chemical Engineering and PhD candidates Dongwoo Lee, Jeonghoon Park, and Seokwoo Kim from the Department of Mechanical Engineering at Pohang University of Science and Technology (POSTECH) successfully demonstrated bound states in the continuum through the utilization of an acoustoelastic coupling structure for the first time. The research findings have been published in Extreme Mechanics Letters, one of the world’s most influential journals in the field of mechanics.
The research team designed an experiment setup aimed at verifying the existence of the BIC phenomenon through the interplay of sound and elasticity. Commencing with the fabrication of an elastic bar resembling a stick, the team proceeded to induce vibrations in the elastic bar by means of a shaker. Subsequently, air injection at a predetermined location on the elastic bar engendered coupling between sound and elasticity.
In the experiment, when the frequency of the elastic progressive wave aligned closely with the resonance frequency generated within the acoustic cavity, a strong interaction manifested, resulting in the complete reflection of the progressive elastic wave. In essence, the elastic wave reverted back along the direction it came from, becoming indefinitely confined within a certain space, similar to the behavior observed when encountering a mirror, despite having ample room for forward propagation. While many studies have explored the utilization of bound states in the continuum, this research represents the first instance of unveiling the BIC phenomenon through the combination of elasticity and sound.
Professor Junsuk Rho emphasized the potential implications of the findings, “This study illustrates that applications of acoustoelastic coupling can be expanded to vibration focusing and energy storage.” He added, “The findings from this research hold promise for diverse applications including the development of filters capable of selectively isolating specific frequencies or the advancement of energy harvesting methodologies that convert kinetic energy into electric energy.”
The study was conducted with the support from the Ministry of Science and ICT and the National Research Foundation of Korea.
END
[Attachments] See images for this press release:
ELSE PRESS RELEASES FROM THIS DATE:
2023-07-12
Policy-makers are being urged to take notice of a University of Otago study that confirms that undertaking a short programme of high intensity interval training before surgery can substantially help with recovery.
The study, published in the journal Surgery, reviewed and analysed 12 studies including 832 patients who had undertaken preoperative high-intensity interval training. Such training involves repeated aerobic high-intensity intervals at about 80 per cent of the maximum heart rate followed by active recovery.
Lead investigator Dr Kari Clifford says the study included all types of major surgeries – those expected ...
2023-07-12
Lyon, France: Lithium is becoming the new gold, with rocketing use in lithium-ion batteries in electric cars, computers, and portable devices driving up the price and affecting the supply of the relatively rare metal. Scientists are on the verge of developing a way of using sodium to replace some of the lithium, so driving down costs and guaranteeing the supply.
Recently scientists have looked at dispensing with lithium altogether and instead using sodium or other elements in high quality batteries. Sodium is cheaper and more available (it’s found in seawater, as sodium chloride), but they have ...
2023-07-12
This year’s Presidential Symposium places plant science within a larger context, spotlighting the connections between plants and humanity. Accordingly, ASPB President Gustavo MacIntosh selected speakers with a broad array of backgrounds and expertise. Yet when the Presidential Symposium takes place Saturday, August 5, at 1:30 pm, you’ll find they agree on critical fundamentals.
“Humans are totally dependent on plants for food,” began Barbara Schaal of Washington University.
“When it comes to agriculture, plants and people are really ...
2023-07-12
Tiny fish called Trinidadian guppies have surprised scientists when faced with the so-called “volunteer’s dilemma”.
The idea of the dilemma is that individuals are less likely to cooperate if they are in a large group.
Various studies have demonstrated this in humans – but guppies appear to buck the trend.
In the new study, by the University of Exeter, guppies in larger groups were more likely to risk approaching a predator to gather information for the shoal.
“When faced with a possible predator, guppies have to balance risks,” said Rebecca Padget, from Exeter’s Centre for Research in Animal Behaviour.
“At least one ...
2023-07-12
An investment of £53 million in six research centres will drive forward change in the energy system and help to meet the UK’s net zero target by 2050.
The energy research centres will boost knowledge, create innovative green technologies and reduce demand for energy to achieve greener, cleaner domestic, industrial and transport energy systems.
UK Research and Innovation (UKRI) has awarded:
£15 million for a new Energy Demand Research Centre that will provide solutions for energy demand reduction, understand the impact on consumers, and enable equitable policy decision-making.
£17.5 ...
2023-07-12
Mars rovers have teams of human experts on Earth telling them what to do. But robots on lander missions to moons orbiting Saturn or Jupiter are too far away to receive timely commands from Earth. Researchers in the Departments of Aerospace Engineering and Computer Science at the University of Illinois Urbana-Champaign developed a novel learning-based method so robots on extraterrestrial bodies can make decisions on their own about where and how to scoop up terrain samples.
“Rather than simulating how to scoop every possible type of rock or granular material, ...
2023-07-12
An estimated 50 million individuals in the United States struggle with the challenges of cocaine or alcohol use disorders, according to the National Institutes of Health (NIH). Beyond the well-documented health risks, addiction to these substances detrimentally affects our cognitive flexibility, which is the ability to adapt and switch between different tasks or strategies. Although previous research has hinted at this connection, the underlying reasons for this cognitive impairment remain elusive.
Cognitive flexibility is a crucial element in various domains of our life, including ...
2023-07-12
AURORA, Colo. (July 11, 2023) – Researchers at the University of Colorado Anschutz Medical Campus have found that cannabidiol (CBD), often used to treat anxiety and nausea, can potentially harm a developing fetus.
The paper was published in Molecular Psychiatry today.
People consume cannabis or a non-psychoactive component cannabidiol (CBD) to help with nausea and anxiety during pregnancy because they think it is safe and healthy. But CBD crosses the placenta and accumulates in the fetal brain.
Until now, no one knew how fetal exposure to CBD affected brain development, said Emily ...
2023-07-11
Fine particulate matter comes from wood burning, power generation, motor vehicles and other combustion sources that emit tiny particles into the air. At only 2.5 micrometers or smaller, these particles are small enough to be inhaled and cause lasting damage to the heart and lungs. Known as PM2.5, exposure to these particles is a leading mortality risk factor in India and the surrounding region of South Asia.
A new study by researchers in Randall Martin’s lab in the McKelvey School of Engineering at Washington University in St. Louis evaluated the contribution of various emission sectors and fuels to PM2.5 mass for 29 states in India ...
2023-07-11
Daniel Becker, Ph.D., an assistant professor of Biology in the Dodge Family College of Arts and Sciences, has received an Oak Ridge Associated Universities Ralph E. Powe Junior Faculty Enhancement Award for his continued research on bat migration in western Oklahoma.
“We’re studying migratory Mexican free-tailed bats and the pathogens they might carry that are possible threats to human or wildlife health,” Becker said. “This award allows us to purchase the microchips we implant in the bats and ...
LAST 30 PRESS RELEASES:
[Press-News.org] Bound states in the continuum is possible in the acoustoelastic coupling
