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Researchers have developed a dolphin-inspired compact sonar with a new echo processing method.
The sonar allows for clearer visual imaging underwater compared to the conventional signal processing method of visualizing sound echoes.
Underwater imaging sonars are an essential technology for ocean exploration. Biomimetic sonars inspired by marine mammals such as dolphins are an emerging development in this field.
The new sonar incorporates information on the sparsity of objects which helps interpret sound echoes better. This processing method is based on the hypothesis that dolphins use prior information about their environment, apart from broadband sound pulses, to interpret their echoes.
Compared to other sonars of similar sizes and purposes, the new sonar provides a better trade-off between sonar-image clarity, the number of sensors, and the size of the sensor array used. Conventional methods of processing sound echoes usually break down when sensors are too few or spread out.
However, the new sonar processing method will be able to extract information and still yield image clarity in such a scenario.
Scientists at the National University of Singapore observed that dolphins were able to acoustically scan objects underwater and pick matching objects visually, demonstrating that a dolphin’s sound echoes emitted off an object contain information of the object’s shape. They then recorded dolphin echoes emitted when scanning an object underwater.
Based on their observations, the team built a biomimetic sonar that replicates a dolphin’s sonar. The sonar, which is about 25 cm (about 10 inches) in width and around the size of a dolphin’s head, is designed to emit sharp, impulsive click sounds similar to a dolphin’s echolocation.
Three transmitters are used to send sounds from different directions. The researchers then processed the sounds from both the dolphin and their sonar to visualize what the echoes revealed about the object shape.
To complement the hardware, the team came up with an innovative software that allowed the sonar to improve the visualization of the echoes.
Based on the hypothesis that dolphins use prior information to process their echoes, the researchers incorporated the concept of sparsity into the sonar’s software. This assumes that out of the space scanned, only a small percentage is occupied by the object.
“Using prior information, such as the idea of sparsity, is intuitive. It is something humans do all the time—we turn our understanding of reality into expectations that can speed up our inferences and decisions,” says Hari Vishnu, senior research fellow at NUS Tropical Marine Science Institute (TMSI).
“For example, in the absence of other information, the human brain and vision system tend to assume that in an image, the light on an object will be falling from above.”
The researchers demonstrated the effectiveness of the software when it was able to visualize information from a dolphin’s sonar echoes when scanning an object, as well as sonar signals produced by their compact sonar.
A conventional approach of processing both sonar echoes resulted in noisy images. However, the new processing approach gave better resolution and therefore sharper images. The software is also able to generate visualizations with a mere three clicks from the sonar, thus allowing it to be operationally fast.
The new sonar processing method could have potential benefits in underwater commercial or military sonars. For example, it could be used to scan the seabed to search for features that can be used to aid navigation. The sonar’s compactness also makes it suitable to be mounted on underwater robots for ocean exploration.
The study appears in Communications Engineering.
Source: NUS
The post Dolphins inspire sonar for clearer underwater images appeared first on Futurity.
Scientists have gained new insights into how the brain’s internal compass gives us a sense of direction.
The findings shed light on how the brain orients itself in changing environments—and even the processes that can go wrong with degenerative diseases like dementia that leave people feeling lost and confused.
“Neuroscience research has witnessed a technology revolution in the last decade allowing us to ask and answer questions that could only be dreamed of just years ago,” says Mark Brandon, an associate professor of psychiatry at McGill University and researcher at the Douglas Research Centre who co-led the work with Zaki Ajabi, a former student at McGill University and now a postdoctoral research fellow at Harvard University.
To understand how visual information affects the brain’s internal compass, the researchers exposed mice to a disorienting virtual world while recording the brain’s neural activity. The team recorded the brain’s internal compass with unprecedented precision using the latest advances in neuronal recording technology.
This ability to accurately decode the animal’s internal head direction allowed the researchers to explore how the head-direction cells, which make up the brain’s internal compass, support the brain’s ability to reorient itself in changing surroundings.
Specifically, the research team identified a phenomenon they call “network gain” that allowed the brain’s internal compass to reorient after the mice were disoriented.
“It’s as if the brain has a mechanism to implement a ‘reset button’ allowing for rapid reorientation of its internal compass in confusing situations,” says Ajabi.
Although researchers exposed the animals in this study to unnatural visual experiences, the authors argue that such scenarios are already relevant to the modern human experience, especially with the rapid spread of virtual reality technology.
These findings “may eventually explain how virtual reality systems can easily take control over our sense of orientation,” adds Ajabi.
The results inspired the research team to develop new models to better understand the underlying mechanisms.
“This work is a beautiful example of how experimental and computational approaches together can advance our understanding of brain activity that drives behavior,” says coauthor Xue-Xin Wei, a computational neuroscientist and an assistant professor at the University of Texas at Austin.
The findings also have significant implications for Alzheimer’s disease. “One of the first self-reported cognitive symptoms of Alzheimer’s is that people become disoriented and lost, even in familiar settings,” Brandon says.
The researchers expect that a better understanding of how the brain’s internal compass and navigation system works will lead to earlier detection and better assessment of treatments for Alzheimer’s disease.
The study appears in the journal Nature.
The Natural Sciences and Engineering Research Council of Canada and the Canadian Institutes of Health Research funded the work.
Source: McGill University
The post Disoriented mice shed light on the brain’s internal compass appeared first on Futurity.
Enlarge / Apple allegedly still holds a ‘grudge’ against Google ever since co-founder Steve Jobs called its rival Android operating system a "stolen product." (credit: FT montage/Reuters)
Apple is taking steps to separate its mobile operating system from features offered by Google parent Alphabet, making advances around maps, search, and advertising that have created a collision course between the Big Tech companies.
The two Silicon Valley giants have been rivals in the smartphone market since Google acquired and popularized the Android operating system in the 2000s.
Apple co-founder Steve Jobs called Android “a stolen product” that mimicked Apple’s iOS mobile software, then declared “thermonuclear war” on Google, ousting the search company’s then-CEO Eric Schmidt from the Apple board of directors in 2009.
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